WATERLOO — Three construction workers have been injured in Waterloo on-the-job accidents. Two were hurt at the TechWorks campus Monday afternoon. Firefighters say the two were on a lift when part of a brick wall came down, injuring them. They were taken to a hospital for treatment of non-life-threatening injuries. Authorities say a man working at the former Hostess Wonder Bread bakery in downtown Waterloo fell through the roof Monday morning while workers were removing vents.